The goal of this project is the development of a specific inactivator for proteins -- enzymes or receptors -- that bind substrate carbonyls as Schiff bases. The protein chosen for initial studies is Acetoacetate Decarboxylase, and the first objective is the characterization of its active site, so that the inactivator may be well designed. Since the primary functionality -- the episilon-amino group of a lipine residue --has already been characterized, the question is whether other functionalities play a role in the action of AAD. One specific question is whether decarboxylation by AAD proceeds with inversion or retention of sterochemical configuration. Once the active site is characterized in this fashion, the inactivator can be designed. The basic strategy is to use a suicide inactivator -- specifically, a bifunctional molecule that, when one end is bound as a Schiff base, will cyclize to inhibit irreversibly the amino group of the active site.